Weed clearing for wild flower area

Because of a bit of a drainage problem, the new owner of the field next to my garden (rural situation near Edinburgh) has dug a drain and fenced on the far side of it.  The result is a 30m x 4m strip of isolated and abandoned ground which runs to a serious weed problem each summer - nettles, thistles and cleavers.

I had an opportunity to speak to the guy recently and he is quite happy if I take it in hand and wild flower it.  Can someone give me some advise as to where to start on this.  My thinking at the moment is to broad leaf weed kill to allow field grass to establish and to scatter sow over that - will that work?  Also where can I get larger quantities of wild flower seed?   I have a medium size cultivator but wouldn't be able to get it in without removing a fence.

Thanks for any help.
Rob

Sounds like you have wild flowers already, nettles, thistles and cleavers   

I would spray off everything as the coarse grasses will out-compete a lot of your wild flower, mind any run off into the water course. You need to balance the work involved in removing your fence with the work involved in rotovating. However I wouldn't rotovate if there are serious perennial weeds. Time for some exercise 

Choose a mix containing yellow-rattle which will help keep the grass at bay. Internet search for bulk seed merchants, garden centres are way too expensive.
This year you could be growing some of the wild flowers (perennials) you want as plug plants so you can get a head start when the land is ready.